| 摘要 |
1526571 Preparation of 2,3,5-trimethyl hydroquinone SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV 17 Feb 1977 [19 Feb 1976] 06606/76 Heading C2C A process for the preparation of 2,3,5-trimethylhydroquinone by (a) catalytically oxidizing 2,3,5- or 2,3,6-trimethylphenol with oxygen in the presence of a cobalt chelate complex, e.g. N,N<SP>1</SP>-ethylene bis (salicylideneiminate)- cobalt (II), as catalyst and dimethylformamide (DMF) as solvent medium, and (b) catalytically hydrogenating the 2,3,5-trimethyl-p-benzoquinone (TMQ) thus formed in the presence of a noble metal catalyst, e.g. palladium supported on an aluminium oxide carrier, is characterized in that the reaction mixture from step (a) is treated with di-n-butyl ether (DBE) and water to form a DBE phase containing TMQ, a precipitate comprising the catalyst and an aqueous phase containing DMF, and the DBE phase is separated from the precipitate and the aqueous phase and - subjected to the catalytic hydrogenation of step (b).
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